import pandas as pd

def contains_code(crs_codes, code_list):
    codes = str(crs_codes).split(';')
    return any(code in code_list for code in codes)

def filter_projects(df, crs3_list, crs5_list, sdg_str):
    if crs3_list != [] or crs5_list != [] or sdg_str != "":
        if crs3_list and not crs5_list:  
            df = df[df['crs_3_code'].apply(lambda x: contains_code(x, crs3_list))]
        elif crs3_list and crs5_list:  
            df = df[df['crs_5_code'].apply(lambda x: contains_code(x, crs5_list))]
        elif not crs3_list and crs5_list:
            df = df[df['crs_5_code'].apply(lambda x: contains_code(x, crs5_list))]

        if sdg_str != "": 
            df = df[df["sgd_pred_code"] == int(sdg_str)]

        return df